Sift flour into a large enough bowl. Mix milk, oil, egg and salt and add. Mix everything with a ladle, then knead until the dough is soft. Wrap in plastic wrap and rest at room temperature for half an hour.
In the meantime, cook the filling: Rinse fresh spinach thoroughly and drain. Thaw frozen spinach. Remove the peel from the onion and chop.
Melt the butter. Sauté the onion in it until light yellow. Add spinach, season with salt and cook for about 5 minutes, turning. Drain in a sieve and squeeze well. Cool.
Heat the clarified butter. Add the mince and roast, turning, until it has lost its red color. Season lightly with salt. Cool.
Mix curd cheese, egg and Sbrinz in a baking bowl and season heartily with salt, pepper and nutmeg. Add the minced meat.
In a small pan, melt the butter.
Roll out the dough thinly on a floured surface. Then roll out paper-thin over the back of your hand. Place a clean kitchen towel under the dough. Brush the dough with butter. Spread the spinach evenly on the top half of the dough, leaving a 5 cm margin on each side. Form the mince on top of the spinach. Fold the sides over the filling, then roll the strudel up tightly using the kitchen towel. Slide, seam side down, onto a baking sheet lined with parchment paper. Brush with butter.
Place the strudel